Plant growth regulators

ABSTRACT

THE SUBSTITUTION OF SEMICARBAZONES OF 2&#39;&#39;,6&#39;&#39;-DIHALOBENZALDEHYDES BY 1-ALKYL GROUPS AND 3-ALKYLSUFONYL OR 3ARALSUFONYL GROUPS, PROVIDES COMPOUNDS WHICH ARE ACTIVE PLANT GROWTH REGULATORS. PLANT GROWTH REGULATION PROVIDES A MORE EFFICIENT MEANS OF GROWING FOOD-PRODUCING PLANTS AND THE LIKE.

3,709,936 PLANT GROWTH REGULATORS Tomas L. Fridinger and Edward L. Mutsch, Woodbury Township, Washington County, and David R. Pauly, Stillwater, Minn., assignors to Minnesota Mining and Manufacturing Company, St. Paul, Minn. N Drawing. Filed Nov. 16, 1970, Scr. No. 90,074 Int. Cl. C07c 133/02 US. Cl. 260-554 Claims ABSTRACT OF THE DISCLOSURE The substitution of semicarbazones of 2,6-dihalobenzaldehydes by 1-alkyl groups and 3-alkylsulfonyl or 3- arylsulfonyl groups, provides compounds which are active plant growth regulators. Plant growth regulation provides a more efficient means of growing food-producing plants and the like.

BACKGROUND OF THE INVENTION The compounds of the present invention are substituted semicarbazones of certain benzaldehydes. More specifically they are semicarbazones of 2,6'-dihalobenzaldehydes substituted by l-alkyl groups and 3-alkylsulfonyl or 3- arylsulfonyl groups. The compounds of the present invention are useful as plant growth regulators and may be used with other various suitable adjuvants, both inert and active.

The problem of population explosion and food shortage have become quite serious recently and are widely acknowledged. The search for methods to improve the efficiency of agricultural production continues vigorously and in many ways. Equipment, improved varieties of plants and chemical control of plant pests continue to advance in sophistication. Plant growth regulating chemicals have the potential to play an important role in the struggle against hunger. Such chemicals may be compared to hormones and other food supplements to the human diet as they help the plant to do a more efficient job in its production of food.

Plant growth regulating utility is relatively uncommon, although widely sought. In some cases chemical compounds may be plant growth regulators at low concentrations and may be very phytotoxic, that is herbicidal, at high concentrations. An example of this is 2,4-dichlorophenoxyacetic acid. In fact, the term plant growth regulator is sometimes used to include herbicidal properties, although it is not used herein in that sense. Plant growth regulators may stimulate or retard growth of the plant or may alfect the growth of one particular part of the plant without affecting other parts of the plant. In some cases, plant growth regulators may be found which direct the energy of the plant to a particular aspect of its development which is most desirable, that is they may increase the yield of the edible portion of the plant. This may occur by a variety of mechanisms, for example increased flowering, increased bud set, enlargement of the edible portion and the like. Such effects are particularly advantageous.

The methods for distribution of agricultural chemicals in general, and plant growth regulators in particular, utilize the scattering of a relatively small amount of diluted material over a large area. Examples of regulators so used are maleic hydrazide and gibberillic acid. Accidental localization of the effective ingredient can occur, however, resulting in phytotoxicity if the ingredient is herbicidal at higher concentrations. For this reason plant growth regulators with very low phytotoxicity would be desirable.

"United States Patent 0 3,709,936 Patented Jan. 9, 1973 According to the present invention there are provided compounds of the formula wherein X is halogen; R is alkyl and haloalkyl having from one to four carbon atoms, phenyl and substituted phenyl; and R is alkyl having from one to four carbon atoms. The compounds find use as plant growth regulators and have the advantage of little or no phytotoxicity.

In the preferred embodiment of the present invention, X is chlorine or bromine, although it may also be fluorine or iodine. Preferably, one X is always chlorine. In the most preferred embodiment, both Xs are chlorine as the corresponding starting materials are most readily available.

R' may be a straight or branched chain alkyl of one to four carbon atoms, but is preferably methyl or ethyl, methyl being preferred. R may be straight or branched chain alkyl of one to four carbon atoms, but it is preferably methyl or ethyl, methyl being preferred.

When R is haloalkyl having from one to four carbon atoms, the halogen may be fluorine, chlorine or bromine, but is preferably fluorine or chlorine. In the preferred embodiment, R is generally one or two carbon atoms partially halogenated. Most preferred are compounds wherein R is chloromethyl or fluoromethyl.

When R is substituted phenyl, one to five Substituents may be present on the ring. These substituents may be the same or different. Substituents which may be present include halogen, alkoxy, alkyl, nitrol and haloalkyl wherein the alkoxy, alkyl and haloalkyl groups have from one to four carbon atoms. Preferably preferred Substituents are halogen and alkoxy.

The compounds of the invention are prepared, generally, by the reaction of novel 2,6-dihalobenzaldehyde alkyl-, haloalkyland arylsulfonyl. hydrazones with alkyl isocyanates. This reaction is preferably carried out in a suitable nonreactive solvent which dissolves the hydrazone, for example ketones such as acetone, esters such as ethyl acetate, halogenated hydrocarbons such as dichloromethane, and the like. An excess of the isocyanate is generally used to facilitate the reaction. The reaction may be run at room temperature, but generally requires higher temperatures, such as the reflux temperature of the solvent, and may require extended refluxing for two to three days although refluxing for 1 to 48 hours has been found sufficient for most applications. Preferably, the reaction is run in the presence of a suitable catalyst such as a tertiary amine of which triethylamine is most preferred.

Because the reaction is sluggish, it may be necessary to separate the product from unreacted starting material by fractional crystallization, selective extraction or elution chromatography. The products obtained are generally solids. The synthetic reaction is illustrated by the following equation:

The alkyl isocyanates useful in the process of the above equation are well known in the art. The novel hydrazone intermediates are prepared by the reaction of a 2,6- dihalobenzaldehyde with an alkylsulfonyl, haloalkylsulfonyl or arylsulfonyl hydrazide. Some 2,6-dihalbenzaldehydes are readily available and some others are reported in the chemical literature. See, for example, G. Lock, Berichte, vol. 68, p. 1505 (1935); J. F. Bunnett, et al., J1A.C.S., vol. 83, p. 2512 (1961); and British Pat. No. 1,080,167, issued Aug. 23, 1967. All of the 2,6-dihalobenzaldehydes are available through the use of the The following non-limiting examples are given to illustrate the invention more specifically, particularly with synthetic techniques reported for the preparation of such respect to the Preparation 0f the novel intermediates f compounds. s f the k l d lf lh d id novel and valuable compounds of the present invention. are known in the art, and all of the hydrazides may be prepared by known synthetic methods such as reaction 'EXAMPLE 1 of the sulfonylhalides with hydrazine. The novel halo- T fr d t f 7 3 f 4 b b alkylsulfonyl hydrazides disclosed herein are not reported o a s 1 re mlx 0 o mmo f' in the literature. sulfonylhydrazlde (0.029 mole) in 50 ml. of water is The novel hydrazone intermediates of the invention i g gg i zg g g f i i ?l g izfi'fi ggg ggizfi ti gggg 'n reaction: l are Prepared accordmg to the follow g precipitates and 500 ml. of ethanol is added. The mixture X is heated to reflux and maintained at reflux temperature for one hour. The solution is then filtered hot and al- CH0 4- NH2NHSO2R- 0H 11111150 1! lowed to cool slowly. The precipitate is collected by filtration and washed three times with 75 ml. of water. The x X white solid is 2,6-dichlorobenzaldehyde-4-bromobenzene- The hydrazide is first reacted with the benzaldehyde. sulfonyl hydrazone, M.P. 181l83 C. The mixture is then dissolved in refluxing ethanol and Analy is.Calculated for C13 9 2 2 2 (P the reaction is heated at reflux temperature (approxi- C, 38.3; H, 2.2; N, 6.9. Found (percent): C, 38.5; H, mately 80 C.) for one to several hours to insure the 2.1; N, 6.9. completion of the reaction. The product generally is ob- Other 2,6-dihalobenzaldehyde arylsulfonyl hydrazones tained as a solid precipitate upon cooling of the reaction which are prepared according to the method of Example mixture. 1 are given in the following table.

TABLE I Melting Ex. point No: Compound (in C.)

2 2,6-dichlorobenzaldehyde benzenesulfonyl hydrazone 125-130 3 2,6-d chlorobenzaldehyde 4-methylbenzenesulfonyl hydrazone 189-193 4 2,6-d ehlorobenzaldehyde 4-nitrobenzenesulfonyl hydrazone 193-197 2,6-d1chl0robenzaldehyda 4-rnethoxybenzene sultonyl hydrazone 145. 206-209 162-167 9 2,6-dichlorobenzaldehyde Z-nitrobenzene sulfonyl hydrazone 10 2,6-d1chlorobenzaldehyde 3,4-dieh1orobenzenesulfonyl hydrazone 188. 5-191 11-. 2,6-d lchlorobenzaldehyde 2,5-dichlorobenzenesnlfonyl hydrazone" 203 208 12.. 2,6-d1ohl0robenzaldehyde 4-chloro-2-nitrobenzenesulfonyl hydrazon 13 2,6-dichlorobenzaldehyde pentafluorobenzenesulfonyl bydrazone...

2,6-dichlorobenzaldehyde 4-chloro-3-nitrobenzenesulfonyl hydrazone. 15.- 2,6-d1chlorobenza1dehyde 2,3,4-trichlorohenzenesulfonyl hydrazone.

16--- 2,6-dichlorobenzaldehyde 4-trifluoromethylbenzenesulfonyl hydrazone The plant growth regulating activity of the compounds of the invention was observed by known screening tests on several plant species. The plants were sprayed to runoff with a solution of the novel compounds of the invention in acetone with a surfactant such as Tronic which is a mixture of alkyl aryl oxyethylene glycols mixed petroleum distillates, alkyl sulfates and alkyl amine acetates manufactured by Colliodal Products Co. The concentration of the chemical is 2,000 parts per million and the surfactant concentration is 0.25 to 1.0 percent. The plants were checked daily for any effect or alteration on the development of the plant compared to untreated controls. The compounds of the invention were found to be active in producing plant growth regulatory efiects. In particular, bean plants (Pinto beans) were found to undergo dwarfing of the plant with increased bud and bean production. Such regulation was noted after two to three weeks. Such an effect is extremely desirable, suggesting that more plants could be planted in a given area while each plant produces more beans.

,Among the most active of the compounds were the following: 2',6'-dichlorobenzaldehyde 1-methyl-3-(methanesulfonyl) semicarbazone 2,6'-dichlorobenzaldehyde semicarbazone 2',6'-dichlorobenzaldehyde 1-methyl-3-(ethanesulfonyl) semicarbazone 1-ethyl-3-(methanesulfonyl) EXAMPLE 17 To a stirred solution of 7.7 gm. of methanesulfonylhydrazide (0.07 mole) in 75 ml. of water is added a solution of 12 gm. of 2,6-dichlorobenzaldehyde (0.069 mole) in ml. of ethanol in one batch. A solid precipitates after which 300 ml. of ethanol is added. The solution is heated to reflux temperature and maintained at reflux for one hour. The mixture is filtered hot and allowed to cool slowly. The precipitate is collected by filtration and washed thoroughly with water. The white solid is 2,6-dichlorobenzaldehyde methanesulfonyl hydrazone, M.P. -182 C.

Analysis-Calculated for C H CI N O S (percent): C, 36.0; H, 3.0; N, 10.5. Found (percent): C, 36.0; H, 3.0; N, 10.6.

Other 2,6-dihalobenzaldehyde alkylsulfonyl and haloalkylsulfonyl hydrazones which are prepared according tobtihe method of Example 17 are given in the following ta e.

18..-- 2,6-dlchlorobenznldehyde ethanesulfonyl hydrazone, 158-163 19 2,6-dlchlorobenzaldehyde butanesulfonyl hydrazone- 96-99 20- 2,6-dlcl1lorobenzaldehyde fiuoromethanesulfonyl 132-135 hydrazone.

21 2,6-dtch1orobenzaldehyde ehloromethanesulfonyl 127-128 hydrazone.

EXAMPLE 22 mole) in 20 ml. of acetone. The mixture is stirred cold To a cold stirred solution of 9.0 gm. of 2,6-dichlorofor two hours t temperature for benzaldehyde methanesulfonyl hydrazone ((1034 mole) teen hours, and finally 1t is heated to reflux and maintamed in 100 ml. of acetone and 4 drops of triethylamine is added, at reflux temperam. one The solvent i dropwise, 4 gm. of methyl isocyanate (Q07 mole) in 30 5 moved by evaporation in vacuo to give a solid which 1s m1 of acetone. The mixture is Stirred at 1.00m tempera: recrystalllzed fror n a hexane-chloroform mixture. The ture for about 65 hours, then heated to reflux and m'ainfirst .crop of Preclpltate 1S separated. and 1s found to be tained at a reflux temperature for one hour. The solvent Starting material The filtrate ptrnally evaporated E is removed by evaporation in vacuo to give an oil which a secqnd crop 1s c1lected.wh1ch is found Starting crystallizes. The solid is recrystallized twice from a hexmatenalt Fqrther evaporanqn of the filtrate gwes aathlfd ane chloroform mixture to give white solid 2',6'-dichlorocrop which to be dlfierent from stalitmg .matenal benzaldehyde 1 methyl-3-(methanesulfonyl)semicarbaficcordfng t0 Its mffared spectrum when thls thud 9 Zone 1094140 C- is again recrystallized from a hcxane-chloroform mix- A l 1 ted for C H Cl N O S t ture, the white solid product is 2,6'-dichlorobenzaldchyde C, gagi g 3.4; 11 1 i a i g P 2 1 methyl-3-(4 bromobenzenesulfonyl)semicarbazone,

3.4 N, 13.0. M.P. 121-125" C.

EXAMPLE 23 Analysis. Calculated for C H BrCl N O S (per E h I cent): C, 38.7; H, 2.6. Found.(percent): C, 38.7; H, 2.7.

t y isocyanate is reacted with 2,6-d1chlorobenzalde- EX MPLE 26 hyde methanesulfonyl hydrazone according to Example 0 22 to prepare a White Solid, 2,,6, dichlombenzaldehyde Methyl isocyanate 1s reacted with 2,6-d1chlorobenzaldehyde benzenesulfonyl hydrazone according to Example (methanesulfonyl) senncarbazone 114- to prepare 2',6'-dichlorobenzaldehyde-1-methyl- 3 (ben- Analysl-s. Ca1cu1ated for CuHmClzNaOaS (percent): zilgesufonyl)semicarbazone, a wink: sohd, M.P. 109- c, 39.1; H, 3.8; N, 12.4. Found (percent): 0, 39.0; H, 25 1 4 N 12 6 Analysis.-Calculated for C H Cl N O S (percent): C, 46.6; H, 3.4; N, 10.9. Found (percent): C, 46.6; H,

EXAMPLE 24 3 N 10 9 Methyl isocyanate is reacted with 2,6-dichlorobenzal- I I EXAMPLE 27 dehyde ethanesulfonyl hydrazone according to Example 22 to prepare 2',6-dichlorobenzaldehyde 1-methyl-3- (ethanesulfonyl)semicarbazone, a white solid, M.P. 103- to Example 25 to prepare 2,6, dich10robenza1dehyde Analysis.Calculated for C H Cl N O S (percent): g g l g itilgflyz;gzglesulfonynSemlcarbazone a 39-1; Fmmd (Percent? 38-9; Analysis.--Calculated for c ,H, c1 N,o.,s (percent):

Methyl isocyanate is reacted with 2,6-dichlorobenzaldehyde 4-methoxybenzenesulfonyl hydrazone according EXAMPLE 25 3.6, N, 10.1. Found (percent). C, 46.0, H, To a cold stirred solution of 8.8 gm. of 2,6-dichloro- Other compounds of the invention obtained from the benzaldehyde 4-bromobenzenesulfonyl hydrazone (0.022 reaction of an isocyanate with a 2,6-dihalobenzaldehyde mole) in 90 ml. of acetone and 4 drops of triethylamine alkylsulfonyl or arylsulfonyl hydrazone are shown in the is added, dropwise, 2.3 gm. of methyl isocyanate (0.04 following table:

TABLE III Reactants Example Number Isocyanate Hydrazone Product 28 Methyl 2-chloro-fi-fluorobeuzaldehyde methanesultonyl 2chlogo-fi fluorobenzaldehyde 1-methyL3-(methanesulfonyl)- 7 seem car azone. 2 Ethyl 2,6-dich1or0benzaldehyde 4-nitrobenzenesulfonyl 2,6-digl1lo1goben2aldehyde 1-ethyl-3-(4-nitr0benzensulfonyl)- sem car azone. 30 nButyl. 2,6-dibromobenzaldehyde 4-bromobenzenesu1fonyl 2,6-dijl3r0ngobenzaldehyde 1-n-butyl-3-(4-bromobenzenesulfonyl)- so our azone. 31 Is0pr0pyl 2,6-dichlorobenzaldehyde 4-meth0xybenzenesulf0nyl 2,6-dteh1orobenzaldehyde 1-isopropyl-3(4-methoxybenzenesulfonybsemicarbazone. Methyl 2,6-dichlorobenzaldehyde isopropanesulfonyl 2,6ditihl00benzaldehyde l-methy1-3-(is0propanesultony1)- S8111 Cal azone. 33 ..do 2,6-diiodobenzaldehyde methanesultonyl Zfi-dgodobenzaldehyde 1-methyl-3-{methanesulfonyhsemlcar azone. 34 do 2-chloro-6-bromobenzaldehyde methanesulfonyl- 2-ch10;0-6;)brom0benzaldehyde 1-methyl-3-(methanesu1tonyl)- sem car 820118. 35 do 2,6-dichlorobenzaldel1yde 4-trifluoromethylbenzenesul- 2,6-dichl0robenzaldehyde l-methyl-B-(4-trlfiuor0methylbenzene ionyl. sult'onyD-semicarbazone. 36 do 2,6-dichlorobenzaldehyde 4-fiuorobenzenesululfonyl- 2,6dic hl0 obenzaldehyde 1-methyl-3-(4-flu0r0benzenesulf0nyl)- sem 081' 3120118. 37 .do 2,6-dichlorobenzaldehyde 3,4-dichlor0benzenesulf0ny1 2,6-dichl0r0benzaldehyde 1-methy1-3-(3,4-diehl0r0benzenesulfonyl) semicarbazone. 110.- 2,6-dieh1orobenza1dehyda n-butanesulfonyl 2,6-dighlorobenzaldehyde 1-methyl-3-(n-butanesulfonyl)semi ear azone. 39 .do 2,6-diel1lorobenzaldehyde pentafiuorobenzenesulfonyl 2,6diehl0robenza1dehyde 1-methyL3-(pentafiuorobenzenesulionyl) semicarbazone. 40 .do 2,6-diehlorobenzaldehyde d-methylbenzenesultonyl 2,6-dichlorobenzaldehyde 1-metl1yl-3-(4-methylbenzenesulfonyDsemicarbazone. 41 -d0 2,6-dichlorobenzaldehyde ehloromethane sultonyl 2,6-dicihlo;)benza1dehyde l-methyl-it-(ehloromethanesulionyl)- stem (38! 820118. 42 -do 2,6-dichlorobenzaldehyde fluoromethanesulionyl 2,6-diehloa0benzaldehyde 1-methyl-3-(flu0r0methanesultonyl)- semicar azone. 43 do 2,6-dichlorobenzaldehyde 2,5-dichlorobenzenesulionyl 2,6-dtchlor0benzaldehyde l-methyli-(2,5'diehlorobenzenesulfonyDsemicarbazone. 44 do 2,6-diehlorobenzaldehyde 4-nitr0benzenesulf0nyl 2,6-dleihloilgobenzaldehyde l-methyl-ti-(4-nltrobenzenesulf0nyl)- S8111 03.1 azone. 45 do 2,6-dichlorobenzaldehydo S-nitrobenzenesulionyl 2,fi-dic hlorg benzaldehyde 1-methyl-3-(3-nitrobenzenesulfonyl)- SQmlCHJ DZODB. 46 do 2,6-dich1or0benznldehyde 2,4,fi-trlmethylbenzenesultonyl-- 2,6-dichlorobenzaldehyde 1methyl-3(2,46-trlmethylbenzene sulfonyDsemicarbazone.

7 What is-claimed is:

1 A compound of the formula wherein X is halogen; R can be alkyl and haloalkyl having from one to four carbon atoms, phenyl and substituted phenyl wherein the phenyl substituents are selected from the group consisting of halogen, alkoxy having from one to four carbon atoms, alkyl having from one to four carbon atoms, nitro and haloalkyl having from one to four carbon atoms; and R is an alkyl having from one to four carbon atoms.

2. A compound according to claim 1 wherein X is chlorine.

References Cited UNITED STATES PATENTS 3,352,909 11/1967 Sayigh et al 260-554 3,355,451 11/1967 Hook et a1. 260-554 HOWARD T. MARS, Primary Examiner M. W. GLYNN, Assistant Examiner US. Cl. X.R.

71 119, 120; 252 3ss; 260566 B 

